Beatriz Defez Garcia

Real-time assistance prototype — A new navigation aid for blind people

This paper presents a new prototype for being used as a travel aid for blind people. The system is developed to complement traditional navigation systems such as white cane and guide dogs. The system consists of two stereo cameras and a portable computer for processing the environmental information. The aim of the system is to detect the static and dynamic objects from the surrounding environment and transform them into acoustical signals. Through stereophonic headphones, the user perceives the acoustic image of the environment, the volume of the objects, moving object direction and trajectory, its distance relative to the user and the free paths in a range of 5m to 15m. The acoustic signals represent short train of delta sounds externalized with non-individual Head-Related Transfer Functions generated in an anechoic chamber. Experimental results show that users were able to control and navigate with the system safety both in familiar and unfamiliar environments.

Perception of the sound source position

This paper presents several experiments on sound source localization. They are based on monaural click presented at different interclick intervals (ICI), from 10 to 100 ms. Trains of clicks were presented to 10 healthy subjects. At short interclick intervals the clicks were perceived as a blur of clicks having a buzzy quality. Moreover, it was proven that the accurateness in the response improves with the increase of the length of ICI. The present results imply the usefulness of the interclick interval in estimating the perceptual accuracy. An important benefit of this task is that this enables a careful examination of the sound source perception threshold. This allows detecting, localizing and dividing with a high accuracy the sounds in the environment.

3D CMOS sensor based acoustic object detection and navigation system for blind people

The paper presents a new wearable Cognitive Aid System for Blind People (CASBliP). The prototype device was developed as an obstacle detector, orientation and navigation Electronic Travel Aid (ETA) for blind people. The device provides a binaural acoustic image representation. The environmental information acquisition system is based on an array of 1×64 CMOS Time-of-Flight sensors. Through stereoscopic (binaural) acoustic sounds the device relays the surrounding near and far environment. Experimental results demonstrate that blind users are able to detect obstacles and navigate through unknown and known environments safety and confidently. CASBliP works accurately in range of 15m in distance and 64° in azimuth, providing significant advantages in comparison with currently existing ETA systems.

The influence of the inter-click interval on moving sound source localization for navigation systems

In this paper an analysis of moving sound source localization via headphones is presented. Also the influence of the inter-click interval on this localization is studied. The experimental sound is a short delta sound of 5 ms, generated for the horizontal frontal plane, for distances from 0.5 m to 5 m and azimuth of 32° to both left and right sides with respect of the middle line of the listener head convolutioned with individual HRTFs. The results indicate that the best accurate localization was achieved for the ICI of 150 ms. Comparing the localization accuracy in distance and azimuth is deduced that the best results have been achieved for azimuth. The results show that the listeners are able to extract accurately the distance and direction of the moving sound for larger inter-click intervals.